In the operation of offshore oil wells it is common practice to employ a buoyant tower to which a ship or other vessel, such as a tanker or floating refinery, is moored. In such a system, it is desirable to employ a rigid interconnection between the vessel and the buoyant tower provided with "quick-disconnect" means for permitting the ship to be disconnected from the tower when the need arises. A typical quick-disconnect system comprises a first section which is permanently attached to the buoyant tower and which is adapted for rotation about vertical and horizontal axes, in order to permit the ship to rotate about the point of connection to the tower as well as to roll and pitch in response to the prevailing wind and water conditions. A second section of the quick-disconnect system is connected to the ship, usually as its bow, the two sections being designed to interlock and form a rigid connection between the ship and the tower.
During routine operation of the buoyant tower mooring, it is desired that the section of the mooring system attached to the buoyant tower offer no resistance to the free movement of the ship, the weight of the tower section of the mooring system being in effect supported by the ship through the rigid mooring arm structure. Some provision must be made, however, for supporting the weight of the tower section of the mooring system when no ship is attached thereto, and more particularly immediately after a ship is disconnected therefrom, in order to prevent the tower section of the mooring system from falling under its own considerable weight after the ship is disconnected, and thereby damaging either the tower or the system itself.